With a wireless power transfer technique for wirelessly transferring electric power, a control signal is transmitted or received when electric power is supplied and received. Methods for transmitting or receiving the control signal includes an in-band method with which communication is performed using the same method as an electric power transfer method, and an out-of-band method with which communication is performed using a method that is different from the electric power transfer method. The in-band method, with which the communication rate is as low as 1 Mbps or lower, is frequently used since sufficient performance can be achieved if only the control signal for electric power transfer is transmitted.
On the other hand, in recent years, more and more apparatuses have a high-speed and large-capacity wireless communication function, such as a wireless LAN, in accordance with an increasing demand for a higher data communication rate. A control signal for electric power transfer is sufficiently smaller in size than data that is transmitted or received in general data communication, and if the control signal is transmitted with a high-speed and large-capacity communication system, the influence that the transmission of the control signal gives to transmission of other data is extremely small. For this reason, a method has also been studied for transmitting or receiving the control signal with the out-of-band method, rather than the in-band method, using the aforementioned high-speed and large-capacity communication system (see Japanese Patent Laid-Open No. 2012-075302).
When Bluetooth, a wireless LAN, or the like is used for out-of-band communication, the range of wireless power transfer does not coincide with the range in which communication can be performed, and accordingly there are cases where wireless power transfer cannot be performed even though the control signal can be transmitted or received. For example, in FIG. 8, a first electric power receiving apparatus 802 on an electric power supply apparatus 801 is within an electric power transfer range 804 and also within a control communication range 805. For this reason, the first electric power receiving apparatus 802 can receive electric power, and can also transmit or receive the control signal. On the other hand, a second electric power receiving apparatus 803 is out of the electric power transfer range 804, and is within the control communication range 805. For this reason, the second electric power receiving apparatus 803 can transmit or receive the control signal but cannot receive electric power.
In this situation, a problem arises in that the electric power supply apparatus cannot determine whether or not an apparatus near the electric power supply apparatus is the same as an apparatus transmitting or receiving the control signal. That is to say, in the example in FIG. 8, there can be the case where the electric power supply apparatus 801 is transmitting or receiving the control signal for supplying electric power to/from the first electric power receiving apparatus 802, but the electric power supply apparatus 801 does not supply electric power to the first electric power receiving apparatus 802 and incorrectly supplies electric power to the second electric power receiving apparatus 803.
The present invention has been made in view of the above-described problem, and provides a technique for identifying a partner apparatus to be the target of wireless power transfer.